The latest on that search for flight 370. In a new development, military submarines are heading to the search zone and ABC's David Kerley is tracking the effort. Good morning, David. Reporter: Good morning, George. Good news a submarine arrived in this area but where should it be listening right now? Planes are just returning after searching 85,000 square miles, this larger box, just a portion is where they looked and so far they haven't spotted anything. This is the british submarine the "Hms tireless" but with no wreckage sighted on the surface where does it start looking and listening? Those batteries on the black box pingers were start to fade in a handful of days and the sub has to be within a mile to hear them. The luck with using submarines you have to be in the right place. The water will only conduct it for a certain amount of distance. Reporter: While the military had aircraft in the area, a new Zealand newspaper reports peter Jackson has been enlisted to help too or at least his private jet which reported was to fly over part of the search area. So if the pingers stopped, what next? Sonar scans of the bottom looking for wreckage. That's what found air France in the atlantic. With the help of these math wizards in Virginia. They use statistics and a computer model to figure out the most likely place where the wreckage might be and even in this case, they think it'll work. In fact, it's really the only technique to use at this point when you really need something to constrain the search area because, you're right, they're looking at half the Indian ocean right now. Reporter: Investigators and police say this -- this still appears to be an intentional criminal act. If indeed it was whoever was at the controls may have accomplished what they wanted, making a 777 disappear at least for now.

This transcript has been automatically generated and may not be 100% accurate.

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